FYI, these are back in limited stock. I just received mine and I agree that it's a subtle, but nice improvement. So far I'm getting best results with source on the -50DB socket. Nice to play around with.

Got one of these about a month ago from Pacific Valve for $105 or so - incidentally, after I bought mine, they must be running out of their stock or something because their price jumped up about $20 (!). Anyway, thought I'd give my impressions:

I hadn't done any power conditioning or power-based tweaks prior to the purchase of the Audio-GD outlet, with the exception of some "Iron Lung Jellyfish" Hospital-grade power chords for the Keces and Little Dot, which seemed to make a subtle difference. At first I was forced to use the stock power cable that came with the power filter outlet, which really is dismal in terms of gauge and build quality. I also need to replace the actual in-wall power outlet I'm using it with, since it has terrible grip and has been painted over, one can tell, many times (I live in an apartment). The stock cable for the Audio-GD would cause some audible buzzing/electrical noise in the Audio-GD outlet itself, which, of course, is not a good thing - this only happened if I was manipulating the plugs. All of this prompted me to buy a more robust power cable, which I found on Audiogon in the form of a used Valab "Super High Current" cable which was really thick.

Even with the stock power cable, when I fired up my system, I could immediately tell a difference. At first I went with the Kingwa-recommended DAC plugged into the -70DB socket, amp into the -50DB socket. I used one of the "Direct Output" sockets for the Olimex ADuM4160 USB Isolator's wall wart. It's amazing how much this thing can "color" the sound, and I've done a lot of swapping around. So far, I've settled upon the aforementioned combination of DAC into the -70DB socket and amp into the -50DB, but there have been times where I've put the amp into Direct Output. -50DB for my DAC sounds more "colored," almost fuzzy than the -70DB, so I've found that to be a bad combo. The -70DB for the amp seems to really reduce the amp's overall gain/volume, so that was also a no-go. Again, however, I kept finding myself switching around the amp between -50DB and Direct Output. At times, it seemed like -50DB was too "revealing" - lower-encoded MP3's sounded pretty awful, almost staticy, and I was getting some listening fatigue, whereas FLAC files etc. would be less noticeably inferior.

With the -70DB, -50DB combo, soundstage seemed to open up really, really wide, giving recordings an almost ethereal quality, and the warmth of my Little Dot's tubes was really accentuated - most recordings sounded REALLY analog. Some negatives, besides the revealing quality, is general harshness on some recordings (again, poorer recordings were more susceptible to this) especially in the lower frequencies - which seemed odd, given how simultaneously analog/warm they sounded, and some diminishing of the "impact" and/or perceptibility of some higher frequencies. While the soundstage seems wider (and, at times, "taller"), there is also a strange sense of instruments getting "smushed" together in some recordings - I still had a sense of distinctiveness for individual instruments, but their tonality all seemed very similar - having difficulty describing this. Some dynamics would return if I plugged the amp back into Direct Output, at the expense of the soundstage, ethereal quality, and analog warmth I just mentioned - it sort of "flattened" out the sound to plug it back into Direct Output, sounding much more rounded off, but also much more forgiving of a given recording's bitrate etc. My system is incredibly sensitive/revealing with the outlet, now - weird things like changing the voltage of the Olimex isolator's wall wart to 9V from 12V, for instance, is much less subtle than before, or if I turn "Dither" off in foobar things seem to improve.

When I received the Valab chord (here's a picture = http://pic3.audiogon.com/i/c/f/1305592635.jpg), many of the issues with the -50DB outelt for the amp seemed to round themselves out a bit - less listening fatigue, gain increased, cleared up some of the "grittiness" I would get on lesser quality recordings. I may have picked too high of a gauge of chord, though, as recordings are REALLY gain-y/loud now - I've gone from keeping the volume knob on my Little Dot at 9:00 to keeping it at somewhere between 8:00 and 9:00.

Anyway, I'm still playing around with it - I think I'm going to use it as an opportunity to build around the outlet, maybe get some new RCA interconnects or something. Definitely worth a purchase if you want to put some new life into your system - it makes an undeniable sonic difference.

Currently using Black Sand Violet Z1 as mains to the filter than the asylums to my amps. One with rhodium plated IEC's and one regular. I think the rhodium plated sounds almost silver like with noticeable extension in the high and low region with perhaps larger air/soundstage and the regular brass has better tonality with a better focus on the mids. They both sound great and provide dark background with good detail.

A great alternative on the cheap, the wire is 14AWG. Best part is doesn't require any soldering or skill really, just need to follow instructions. Good bang for the buck!

Have had this thing for three to four months now and have enjoyed it, but have had some odd issues. When I first got the filter, I was forced to use the stock power chord, which is obviously of a gauge and build quality unfitting for the filter, and I remember, at the time, I had an old, painted-over outlet I had to plug it into, and so the chord was getting poor grip with the outlet. Each time I'd play with the chord near the outlet to try to get it to maintain better grip, the filter would emit a buzzing/electrical noise form within its chassis. Anyway, I've since replaced the outlet AND the power chord to a very thick gauge audiophile power chord, and even an "audiophile" outlet (the "Porter Port" from Alan Porter), which have made good sonic differences and the grip is quite a bit better. However, I've been noticing lately that when I power on my headphone amp and DAC the filter is emitting a buzzing/electrical noise - in short, periodic, irregular bursts - similar to the one I experienced with the old outlet and stock power chord, but, again, quieter and shorter. My outlet (and all of the outlets in my apartment, as far as I know!) I've discovered to be ungrounded, despite being three-pronged (meaning there is no ground wire to connect to the grounding screw), so I wonder if it has to do with grounding. The noises only emit for about 2 to 5 minutes after turning on the amp and DAC, and then cease altogether. I also have to really listen to hear them (be physically on the ground with my ear next to the filter or bending over in my chair). They don't seem to happen when I turn on my M-Audio speakers only, which are usually connected to the "direct output" outlet on the filter, only if I turn on the amp and DAC (connected to the -50DB and -70DB outlets, respectively), and, again, only for a short time. Any ideas? I still have a limited warranty active with Pacific Valve, who I bought the filter from, if need be. Anyone know, specifically, if this could be related to my not having any real grounding? Thanks.